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Principle of whitening, purifying and removing natural barite powder


Barite type and barite status

1. Sedimentary type

Block or streak and bean grain structure are associated with minerals such as barite, quartz, clay minerals, pyrite, etc.

2. Hydrothermal type

Associated minerals are compact, gray to white barite, pyrite, chalcopyrite, galena, sphalerite, hematite, fluorite, witherite, etc.

3. Volcanic sedimentary type.

Associated minerals such as barite, siderite, specular iron, etc.

4. Residual slope type.

Easy to choose, high grade associated barite, fluorite, calcite, quartz, etc.

With the depletion of high quality and single barite ores, most barite ores in China are of low grade, closely associated with other metallic and non-metallic ores, which directly affects their industrial value. Barite has different requirements for barite purity, whiteness and impurity content.

The production process of barite filler is:

Barite ore (mainly barium sulfate) is usually dark brown because of its impurities such as Fe2O3, MnO and carbon. In industry, barite ore is crushed and mixed with sulphuric acid and aluminium powder in the reaction tank (i.e. "bleaching") and then washed to produce white barite filler, which is widely used as paper, paint and so on. MnO is an alkaline oxide. Al powder can transform dark colored Fe3+ into light colored Fe2+..

The basic method of whitening and purifying barite ore at present?

1.1 physical purification

The physical purification methods of barite are mainly hand selection, gravity separation, magnetic separation and color separation.

The main basis for hand selection is the difference between barite and associated minerals in color and density. After crushing, barite minerals and gangue minerals can be effectively separated. Massive barite can be selected by hand. For example, pan cun coal mine in Xiangzhou, Guangxi, by hand selection, we can get a rich ore with a particle size of 30 ~ 150mm and BaSO4 content of >92%. Hand-selected method is simple, easy to operate, low equipment dependence and low cost, but it requires high ore and low production efficiency, resulting in a great waste of resources.

Gravity separation is based on the density difference between barite and associated minerals. The raw ore is broken and grind to a certain particle size and enters the gravity separation equipment to separate the gangue so as to eliminate gangue. The barium sulfate content of Hengnan barite ore after gravity separation is over 92%, and the barium sulfate concentration of 84.50% can be obtained from the hand tailings after gravity separation. Magnetic separation is based on the difference in magnetic properties between different ores and the selection of other methods under the action of magnetic force.

Magnetic separation mainly removes some magnetic iron oxide minerals such as siderite, which are usually used in combination with gravity separation to reduce iron content in barite concentrate.

The color sorter is a device that automatically sorts out the heterogeneous particles in granular materials by using photoelectric detection technology according to the differences of optical properties of materials. At present, barite dressing has begun to promote.

1.2 chemical purification

1.2.1 flotation purification

With the continuous development and utilization of high-grade barite ore, it is urgent to strengthen the research and development of low-grade barite ore. Barite is often closely associated with fluorite, calcite, quartz and other minerals. It is difficult to separate barite effectively by traditional gravity separation because of its low grade, fine particle size and complex composition. Flotation can be adapted to various types of barite with complex distribution, so it has become the main method of barite separation at this stage.

Collectors are the key to determine whether barite minerals can be effectively separated. Common collectors can be divided into three types according to their adsorption forms: 1. Anionic collectors mainly based on chemical adsorption; 2. Cationic collectors mainly based on physical adsorption; and 3. amphoteric collectors between the two.

According to the separation process of barite and fluorite, there are two kinds: one is to inhibit barite flotation fluorite, the other is to inhibit fluorite flotation barite. Yu Futao et al. used sodium oleate as fluorite collector, YZ-4 tannin extract combined with sodium silicate and aluminium sulfate as inhibitor to inhibit barite flotation, and finally obtained fluorite concentrate with 96.81% CaF2 grade and 92.44% recovery and barite concentrate with 91.36% BaSO4 grade and 86.75% recovery, which realized fluorite and barite flotation. Efficient separation. Li Mingfeng used sodium dodecyl sulfonate as collector, sodium silicate and citric acid as fluorite inhibitors, and adopted the scheme of restraining fluorite flotation barite. Finally, the barite concentrate with BaSO4 grade of 93.28% and recovery of 94.06% was obtained.

Barite fluorite associated ore, flotation, if the resources are large, in the long run, feasible and worth promoting!

1.2.2 calcination and purification

The calcination process of minerals is characterized by thermal dissociation as a simpler mineral or crystalline transformation of minerals themselves, from one solid-phase pyrolysis to another solid-phase and gas-phase physical change process. Because barite minerals are mixed with impurities such as Fe2O3, Titanium dioxide and organic matter in the bed-forming process, these impurities will make barite lime, green and blue, thus affecting the purity and whiteness of barite, and seriously reducing the use value of barite. Calcination can volatilize organic matter. Calcination can remove impurities which can be decomposed or volatilized at high temperature.

Lei Shaomin et al. calcined barite powder with sulfuric acid pickling at 850 for 2 hours, the whiteness could be increased from 88.19% to 90.64%, and 93.5% after calcining at 950 for 2 hours.

At present, Guizhou Tianzhu mainly uses calcination to remove impurities (organic matter), acid pickling, oxidation and reduction technology to make barite black and white.

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